Does your baby have blueish, brown/blue markings on him that were present since birth? Those benign discoloration of the skin are called mongolian spots. Did you know that over 80% of Asians (especially Koreans) have them as babies compared to only 10% of Caucasian babies?
If your baby has these, make sure your pediatrician takes note of them on your child's medical file. As there have been some people who mistake them for markings caused by abuse.